There are two major
types of high temperature fans - centrifugal and axial:
Centrifugal Wheels:
* Multiblade forward curve wheel. This type of
wheel is usually specified where there is a necessity for large volumes
of flow against low to medium static pressure requirements. The
forward curve blade is that it delivers the same volume of air as
either the backward or radial blade wheel, at a lower fan speed, which
is important due to wheel stresses at elevated temperatures. This
fan is the most common type used in all types of heat treatment
operations except where a buildup of material on the blades could
occur, as wheel unbalance would result.
* Radial Blade, paddle wheel type fans. This
type of wheel is usually specified where there is a necessity for
medium volumes of flow against medium to large static pressures. The
paddle wheel is considered a self cleaning type of wheel. It
could be used where there are various materials or dust in the air
stream. Due to its structurally strong design, it is used in many
heat treatment applications at very high temperatures where maximum fan
longevity is desired.